I am not sure what is causing this but enabling debug of xorg-server I get
these messages:

Popen: `"/usr/bin/xkbcomp" -w 1 "-R/usr/share/X11/xkb" -xkm "-" -em1 "The
XKEYBOARD keymap compiler (xkbcomp) reports:" -emp "> " -eml "Errors from
xkbcomp are not fatal to the X server" "/tmp/server-0.xkm"', fp = 0x8458e20
Pclose: fp = 0x8458e20
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Group width mismatch between key and type
Loaded XKB keymap /tmp/server-0.xkm, defined=0x7f

Is that a bug?